diff --git a/apps/wpm/tasks.py b/apps/wpm/tasks.py
index ac966b18..b28c2e07 100644
--- a/apps/wpm/tasks.py
+++ b/apps/wpm/tasks.py
@@ -79,11 +79,12 @@ def cal_shut_hour(stlogId: str):
             sflogexp, _ = SfLogExp.objects.get_or_create(stlog=stlog, sflog=sflog, defaults={'stlog': stlog, 'sflog': sflog, 'is_current_down': is_current_down, 'title': '停机'})
             # 计算duration
             sf_end, sf_start = sflog.end_time, sflog.start_time
-            duration_item = min(sf_end, st_end) - min(sf_start, st_start)
-            if duration_item < 0:
+            duration_item_delta = min(sf_end, st_end) - min(sf_start, st_start)
+            total_seconds = duration_item_delta.total_seconds()
+            if total_seconds < 0:
                 duration_item = 0
             else:
-                duration_item = duration_item.total_seconds()/3600
+                duration_item = total_seconds/3600
             sflogexp.duration = duration_item
             sflogexp.save()
             # 计算每班的总停机时间